1. Field of the Invention
The present invention relates to an organic light-emitting diode employing a mixed host and a method for fabricating the same and, more particularly, to an organic light-emitting diode employing a mixed host formed through an imprinting process and method for fabricating the same.
2. Description of Related Art
Organic light-emitting diodes (OLEDs) have great potential for next generation lighting and displaying devices due to their superb characteristics, such as being ultra-thin in thickness (1 mm or less), high brightness, wide viewing angle (more than 170°), no backlight requirement, low power consumption, rapid response, high resolution, low heat generation, and flexible in appearance. Hence, the OLEDs attract many attentions in both academics and industry.
As shown in FIG. 1, the structure of the conventional OLED comprises: a substrate 101, an anode 102, a hole injection/transport layer 103, a light-emitting layer 104, an electron injection/transport layer 105, and a cathode 106. The light-emitting layer 104 is located between the hole injection/transport layer 103 and the electron injection/transport layer 105, and the function of the light-emitting layer 104 is to generate or control the combination of holes and electrons which result in emissions.
OLEDs can be roughly divided into polymer-type OLEDs and molecule-type OLEDs, according to the employing host materials. The polymer-type OLEDs is generally prepared through a wet spin-coating process. Although the polymer-type OLEDs with good efficiency can be prepared through the spin-coating process, this method can be hardly used to prepare patterned polymer-type OLEDs. Hence, some researchers have developed new techniques to patterned polymer-type OLEDs i.e. contact printing process or roll-to-roll printing process etc. However, the obtained devices mostly show low efficiency and low brightness. For fabricating molecule-type OLEDs, it is generally using a vacuum evaporation process to prepare a pixel-composing one. Although the obtained molecule-type OLED could be efficient and bright, its processing instrument investment is expensive. Also, it is not easy to fabricate large-area-scale molecule-type OLEDs in this manner. In contrast, an imprinting method can be used to prepare the molecule-type OLEDs with large-area-scale in an easy and low cost way, which the film uniformity and quality are sacrificed in stead.
Therefore, it is demanding to provide an OLED and a method for fabricating the same, which should be focused on solving not only the low efficiency and the low brightness of OLEDs prepared by an imprinting process with polymer hosts, but also the poor film-forming problems of OLEDs prepared by an imprinting process with small-molecule hosts.